End connector for heat exchangers

ABSTRACT

End connector for double tube heat exchangers having parallel sets of concentric tubes forming inner and outer flow passageways. U-shaped return passageways are provided for both of the flow passageways, and these return passageways are in close proximity to each other to enhance heat transfer between them. The end connector is removably mounted to facilitate installation and servicing of the system in which it is used.

United States Patent [191 Rinecker [54] END CONNECTOR FOR HEAT EXCHANGERS [75] Inventor: Uli F. Rinecker, San Francisco,

Calif.

[73] Assignee: Envirotech Park,Calif.

[22] Filed: Apr. 14, 1971 [21] App1.N0.: 134,024

Related U.S. Application Data [63] Continuation of Ser. No. 849,622, Aug. 13, 1969,

Corporation, Menlo abandoned.

[52] U.S.Cl ..l65/l43, 285/157 [51] Int. Cl. ..F28f 9/00 [58] Field of Search ..l65/l43;285/157 [56] References Cited UNITED STATES PATENTS 2,053,780 9/1936 Price et a1 ..165/143 X 1 Mar. 27, 1973 703,177 6/1902 Buffum ..165/178 1,717,395 6/1929 McClatchie ..165/143 1,757,136 5/1930 Pabodie ..165/143 938,476 11/1909 Gottlieb ..165/143 2,545;280 3/1951 Hollmeyer et a1. .....165/143 1,605,987 11/1926 Primary ExaminerCharles J. Myhre Assistant ExaminerTheophil W. Streule, Jr. Att0meyF1ehr, Hohbach, Test, Albritton & Herbert [57] ABSTRACT End connector for double tube heat exchangers having parallel sets of concentric tubes forming inner and outer flow passageways. U-shaped return passageways are provided for both of the flow passageways, and these return passageways are in close proximity to each other to enhance heat transfer between them. The end connector is removably mounted to facilitate installation and servicing of the system in which it is used.

9 Claims, 3 Drawing Figures Richey et a1 ..165/143 END CONNECTOR FOR HEAT EXCHANGERS CROSS-REFERENCE TO RELATED APPLICATION This is a continuation of Ser. No. 849,622, filed Aug.

This invention pertains generally to heat exchangers and more particularly to an end connector for multiple tube heat exchangers.

I-Ieretofore, double pipe heat exchangers have been provided which include a smaller inner pipe concentrically disposed within a larger outer pipe. These pipes form an inner flow passageway within the smaller pipe and an outer flow passageway intermediate the inner and outer pipes. These double pipe heat exchangers provide means for transferring heat between substances such as liquids, gases, and the like flowing in the inner and outer flow passageways.

Double pipe heat exchangers frequently include a plurality of sets of inner and outer pipes. These sets are commonly mounted in a parallel spaced apart relationship and serially interconnected'at their ends. The inner pipes are generally interconnected by means of U-shaped pipes connected to the ends of the inner pipes. A problem exists, however, in interconnecting the outer pipes.

I-Ieretofore, the outer pipes have been cut off some distance away from the U-shaped pipe, and the outer flow passageways have been sealed by welding an annular plate between the inner and outer pipes. The outer pipes have been interconnected by connecting pipes extending normally between the outer pipes. These connecting pipes are generally welded in place or joined by flanges. This construction has been found to be unsatisfactory in several respects. It necessitates considerable cutting, fitting, and welding of the outer pipes and makes installation of the system relatively difficult. There is no heat transfer between the inner and outer flow passageways in the region of the U- shaped pipe since the U-shaped pipe and pipe interconnecting the outer pipes are separated from each other by an appreciable distance. Thus, a substantial heat transfer area is lost. There is also a problem of leakage at the joint between the annular plate and inner pipe as the pipes expand and contract. Furthermore, the pipe interconnecting the outer pipes is difficult to reach for installation and maintenance.

There is, therefore, a need for a new and improved end connector for tubular heat exchangers which overcomes the foregoing and other problems encountered with end connections heretofore provided.

SUMMARY AND OBJECTS OF THE INVENTION The end connector of the present invention provides means for interconnecting the outer flow passageways through a return passageway in which the U-shaped return pipe for the inner flow passageways is disposed. Thus, throughout its entire length, the inner passageway is in close proximity to the outer passageway, thereby providing maximum heat transfer.

v The end connector is removably mounted to facilitate installation and servicing of the system in which it is used.

It is, in general, an object of the invention to provide a new and improved end connector for heat exchangers.

Another object of the invention is to provide an end connector of the above character which enhances heat transfer between the inner and outer flow passageways.

Another object of the invention is to provide an end connector of the above character which is readily installed and maintained.

Additional objects and features of the invention will be apparent from the following description in which the preferred embodiment is set forth in detail in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a front elevational view of one embodiment of a heat exchanger incorporating the present invention.

FIG. 2 is an enlarged sectional view of one of the end connectors in the heat exchanger shown in FIG. 1.

FIG. 3 is an elevational view, partly sectioned, of a coupling used in the embodiment shown in FIGS. 1 and DESCRIPTION OF THE PREFERRED EMBODIMENT A heat exchanger incorporating the present invention comprises a framework including end plates 11, a plurality of sets of elongate tubular members 12 mounted on the end plates in a spaced-apart parallel relationship, and a plurality of end connectors 13 interconnecting the sets 12.

The end plates 11 are generally rectangular and adapted for stacking, as shown in FIG. 1. A pair of oppositely facing, vertically extending U-shaped channel members 14 is provided at each end of the framework. These channel members engage the edges of the end plates 11 and hold them in general vertical alignment. This construction permits the tubular members to expand and contract with changes in temperature without straining the connections to the end connectors. Where the tubular members are longer than about 20 feet, it may be desirable to provide additional supports intermediate the end plates II to prevent sagging of the tubular members.

Each of the sets 12 includes an inner elongate tubular member 16 and an outer elongate tubular member 17. The external diameter of the inner tubular member 16 is less than the internal'diameter of the outer tubular member 17, and the tubular member 16 is concentrically disposed within the tubular member 17. Thus, an inner flow passageway 18 is formed inside the inner tubular member, and an outer flow passageway 19 is formed in the annular region intermediate the inner and outer tubular members.

The end connectors 13 provide means for connecting the sets 12 in series to form continuous inner and outer flow passageways. The free ends of the interconnected sets are provided with connecting flanges 21 and 22. These flanges provide means for connecting the heat exchanger to an external system for delivering and receiving working fluids. The flanges 21 are connected to the inner and outer tubular members and include openings in communication with the inner flow passage 18. The flanges 22 are connected to the outer tubular members and include openings in communication with the outer flow passageways 19.

Each of the end connectors 13 includes means forming an inner return passageway in communication with the inner flow passageways 18 of two of the sets 12 and an outer return passageway in communication with the outer flow passageways 19 in the two sets.

The means forming an inner return passageway comprises a U-shaped return tube 26 removably connected to the ends of the inner tubular members by means of couplings 27. In the preferred embodiment, the couplings 27 are conventional V-band couplings of the type illustrated in FIG. 3.

Each V-band coupling includes a pair of sleeves 28 and 29 which are adapted to be attached to the inner tubular member and return tube, respectively, by conventional means such as welding or threading. The sleeves are formed to include radially extending flange portions 28a and 29a having vertical confronting surfaces 28b and 29b and inclined outer surfaces 280 and 290. An O-ring 31 is disposed in an annular groove 32 formed in the confronting surface of the sleeve 29. A V-band 33 extends circumferentially around the flange portions of the sleeves. This band is formed to include a V-shaped groove 34 having inclined side walls 340 adapted for slidably engaging the inclined surfaces of the flange portions of the sleeves. A clamping ring 36 encircles the V-band and cooperates with the V-band to provide means for urging the flange portions of the sleeves together. The ring 36 includes a radially extending flange 37 at each of its ends, and a bolt and nut assembly 38 engages these flanges to provide 'means for tightening the clamping ring.

Alternatively, other types of coupling devices, such as pipe unions, can be used for joining the return tube to the inner tubular members. Likewise, if desired, the return tube and inner tubular members can be permanently connected together by conventional means such as welding.

The means forming an outer return passageway includes a cover member 41 which cooperates with the end plate 11 to enclose the return tube 26 in a chamber 42 which is in communication with the outer flow passageways 19. The cover member 41 has a curvature generally corresponding to the outer contour of the return tube 26 and is separated therefrom by a distance on the order of the spacing between the tubular members l6 and 17. The cover member 41 includes a flange portion 41a and is mounted to the end plate 11 by means of bolts 43 which extend through the flange portion and the end plate. A gasket 44 is provided between the flange portion and end plate. Alternatively, the cover member 41 can be mounted to the end plate by means of a conventional V-band coupling similar to the type illustrated in FIG. 3 and described hereinbefore.

The outer tubular members 17 are removably mounted on the end plate by means of flanges 26. These flanges are attached to the tubular members by conventional means such as welding or threading, and they are removably mounted to the end plate by means of bolts or cap screws 43 and 47. Gaskets 48 are provided between the flanges 46 and the end plate 1 1.

The end plates 11 are formed to include circular openings 49. These openings are in registration with the openings in the outer tubular members and provide communication between the outer flow passageways l9 and chamber 42. As can be seen in FIG. 2, the inner tubular members 16 extend through the openings 49, and the couplings 27 are located in the chamber 42. Thus, when the cover member 41 is removed from the end plate, the couplings 27 are readily accessible.

Means is provided at one end of the heat exchanger for adjusting the position of the inner tubular member 16 and return tube 26. This means includes a pair of threaded studs 51 and 52 which are secured to the return tube and end plate by conventional means such as welding. The sleeves are mounted in axial alignment with each other and are threadedly engaged by an internally threaded adjusting sleeve 53. In the preferred embodiment the studs are oppositely threaded, and the ends of the sleeve 53 are likewise oppositely threaded.

Thus, the sleeve cooperates with the oppositely Alternatively, the studs 51 and 52 can be provided I with threads of different pitches. Thus, for example, the stud 51 might be provided with a national course thread, and the stud 52 might be provide'cl with a national fine thread. The use of studs having different pitches has been found to provide a very accurate means of adjusting the position of the inner tubular member 16 in the return tube 26.

The heat exchanger and end connectors are preferably fabricated of materials of at least moderate thermal conductivity. Also, it is desirable that these materials have sufficient strength to withstand the pressures commonly encountered in heat exchangers and that they not be subject to attack by the working fluids therein.

It is apparent from the foregoing that a new and improved end connector for heat exchangers has been provided. This end connector keeps the inner and outer flow passageways in close proximity throughouttheir entire lengths to provide maximum heat transfer. A heat exchanger incorporating this end connector is readily installed and maintained. Once the flanges have been attached to the outer tubular members and the coupling sleeves attached to the inner tubular members and return tubes, the heat exchanger can be completely assembled and disassembled using only a wrench.

I claim:

1. In an end connector for heat exchangers of the type having parallel sets of inner and outer elongated tubular members forming inner flow passageways within said inner tubular members and outer flow passageways intermediate said inner and outer tubular members, a return tube of substantially uniform diameter connected to the inner tubular members of two of the said sets and forming an inner return passageway in communication with the inner flow passageways in the two sets, the flow area of said inner return passageway being substantially equal to that of said inner flow passageways, a generally rectangular plate member connected to the ends of said outer tubular members, said plate member having openings in registration with the openings in said outer tubular members, said inner tubular members extending through the openings in said plate member, a cover member removably mounted on said plate member and cooperating with said plate member to enclose said return tube and form an outer return passageway in communication with the outer flow passageways, said outer return passageway being of substantially the same flow area as said outer flow passageways, a first stud member mounted on said plate member, a second stud member mounted on said return tube, said first and second stud members being aligned axially of each other, and a sleeve member cooperating with said stud members for adjusting the position of said return tube relative to said plate member.

2. An end connector as in claim 1 wherein said return tube is removably connected to said inner tubular members in the region bonded by said plate member and said cover member.

3. A heat exchanger having at least three sets of tubular members and a plurality of end connectors of the type defined by claim 1 wherein at least two of said plate members are disposed in the same vertical plane and stacked one on top of the other, there being no rigid connection between said plate members other than the intervening tubular members.

4. In a heat exchanger first, second and third sets of elongated tubular members, each set including an inner tubular member disposed within an outer tubular member and forming an inner flow passageway within said inner tubular member and an outer flow passageway intermediate said inner and outer tubular members; frame means holding said sets in a parallel spaced-apart relationship, said frame means including a first end plate connected to the ends of the outer tubular members of the first and second sets at one end of the exchanger and a second end plate connected to the ends of the outer tubular members of the second and third sets at the other end of the exchanger, said end plates being formed to include openings in communication with the outer flow passageways in the sets to which they are connected; first and second return tubes connected to the inner tubular members of the first and second sets and the second and third sets, respectively, to form inner return passageways in communication with the inner flow passageways in said sets; and a cover member removably mounted on each of said end plates and enclosing one of said return tubes, thereby forming outer return passageways in communication with the outer flow passageways in said sets, said outer return passageways and outer flow passageways together forming a continuous enclosed passageway of substantially uniform cross-sectional area extending from one end of the first set of tubular members to the other end of the third set, said cover members being secured to said end plates by releasable means accessible externally of the exchanger.

5. A heat exchanger as in claim 4 wherein the inner tubular members of said sets extend through the openings in said end plates, and wherein said return tubes are removably connected to said inner tubular members in the regions between said end plates and said cover members.

6. A heat exchanger as in claim 4 wherein said end plates are removably connected to said outer tubular members by flanges carried by said outer tubular members and means removably engaging the corresponding end plates and flanges for drawing them together in sealin relationship.

7. 1% heat exchanger as in claim 4 together with adjustable means connected to each of said end plates and to the corresponding return tubes for positioning said return tubes and inner tubular members within said cover members and said outer tubular members] 8. A heat exchanger as in claim 7 wherein the adjustable means associated with each end plate includes threaded stud members carried by the end plate and the return tube, said stud members being disposed in axial alignment with each other, and an internally threaded sleeve member threadedly engaging said stud members for adjusting the spacing between said end plate and said return tube.

9. A heat exchanger as in claim 4 wherein the releasable means securing the cover members to the end plates includes a plurality of bolts extending in a direction generally parallel to the tubular members, the heads of said bolts being accessible from the outer ends of the cover members. 

1. In an end connector for heat exchangers of the type having parallel sets of inner and outer elongated tubular members forming inner flow passageways within said inner tubular members and outer flow passageways intermediate said inner and outer tubular members, a return tube of substantially uniform diameter connected to the inner tubular members of two of the said sets and forming an inner return passageway in communication with the inner flow passageways in the two sets, the flow area of said inner return passageway being substantially equal to that of said inner flow passageways, a generally rectangular plate member connected to the ends of said outer tubular members, said plate member having openings in registration with the openings in said outer tubular members, said inner tubular members extending through the openings in said plate member, a cover member removably mounted on said plate member and cooperating with said plate member to enclose said return tube and form an outer return passageway in communication with the outer flow passageways, said outer return passageway being of substantially the same flow area as said outer flow passageways, a first stud member mounted on said plate member, a second stud member mounted on said return tube, said first and second stud members being aligned axially of each other, and a sleeve member cooperating with said stud members for adjusting the position of said return tube relative to said plate member.
 2. An end connector as in claim 1 wherein said return tube is removably connected to said inner tubular members in the region bonded by said plate member and said cover member.
 3. A heat exchanger having at least three sets of tubular members and a plurality of end connectors of the type defined by claim 1 wherein at least two of said plate members are disposed in the same vertical plane and stacked one on top of the other, there being no rigid connection between said plate members other than the intervening tubular members.
 4. In a heat exchanger first, second and third sets of elongated tubular members, each set including an inner tubular member disposed within an outer tubular member and forming an inner flow passageway within said inner tubular member and an outer flow passageway intermediate said inner and outer tubular members; frame means holding said sets in a parallel spaced-apart relationship, said frame means including a first end plate connected to the ends of the outer tubular members of the first and second sets at one end of the exchanger and a second end plate connected to the ends of the outer tubular members of the second and third sets at the other end of the exchanger, said end plates being formed to include openings in communication with the outer flow passageways in the sets to which they are connected; first and second return tubes connected to the inner tubular members of the first and second sets and the second and third sets, respectively, to form inner return passageways in communication with the inner flow passageways in said sets; and a cover member removably mounted on each of said end plates and enclosiNg one of said return tubes, thereby forming outer return passageways in communication with the outer flow passageways in said sets, said outer return passageways and outer flow passageways together forming a continuous enclosed passageway of substantially uniform cross-sectional area extending from one end of the first set of tubular members to the other end of the third set, said cover members being secured to said end plates by releasable means accessible externally of the exchanger.
 5. A heat exchanger as in claim 4 wherein the inner tubular members of said sets extend through the openings in said end plates, and wherein said return tubes are removably connected to said inner tubular members in the regions between said end plates and said cover members.
 6. A heat exchanger as in claim 4 wherein said end plates are removably connected to said outer tubular members by flanges carried by said outer tubular members and means removably engaging the corresponding end plates and flanges for drawing them together in sealing relationship.
 7. A heat exchanger as in claim 4 together with adjustable means connected to each of said end plates and to the corresponding return tubes for positioning said return tubes and inner tubular members within said cover members and said outer tubular members.
 8. A heat exchanger as in claim 7 wherein the adjustable means associated with each end plate includes threaded stud members carried by the end plate and the return tube, said stud members being disposed in axial alignment with each other, and an internally threaded sleeve member threadedly engaging said stud members for adjusting the spacing between said end plate and said return tube.
 9. A heat exchanger as in claim 4 wherein the releasable means securing the cover members to the end plates includes a plurality of bolts extending in a direction generally parallel to the tubular members, the heads of said bolts being accessible from the outer ends of the cover members. 